facebook's alright. young ppl use it all the time as any other contact tool, like a mobile phone or aim. Older folks like it to keep in touch once everyone kind of goes their own way. just don't stalk this lady, or at least don't let her know you're stalking her (as in don't comment on all her pictures or what other people write on her Wall). don't worry, she cannot tell how many times u check her profile page haha
but in all seriousness, Facebook is useful but not amazing. i think the "groups" and "applications" things are dumb, as well as a lot of other things on there. Who cares what "group" i'm in? I don't think anybody cares what my activites or favourite music is. inspirational quotes? they're everywhere, nothing special. Careful who you accept as friends as sometimes you can get a random friend request who is probably after your information. i recently "cleaned out" all my "friends" and really dumbed down my profile to just my email and profile pictures and a few other things. i wouldn't ever list your full address or cell phone number. some companies supposedly will look at your facebook, too so be careful about pictures and profanity.
i mostly use mine not to make friends, but so people I really know can get in touch with me (via listed email or writing on the wall). they already know what my favourite movies are and all that, so no need to list it.
so, if you want, go ahead and join. everyone else is. if you don't, no biggie. just be careful because you may not want everyone to see everything about you. i make good use of the Privacy settings